1. Field of the Invention
The present invention relates to a self-lubricating coating composition that comprises an admixture of two specific epoxy resin compositions; a di-epoxide reactive diluent; polytetrafluoroethylene; molybdenum disulfide and mica Moreover, the present invention is directed to a substrate that has the cured form of the above admixture that is either incorporated onto a undamaged surface of the substrate or into damaged or worn areas of the substrate.
2. Brief Description of the Art
Self-lubricating coatings are used for a wide variety of industrial applications, offering a movable linkage connection without the need for lubrication by grease and/or oil. Self-lubricating coating compositions provide a high load capability with lower friction than exhibited by metal/metal bearings contact as well as having a relatively long life without the need for replenishing the lubrication media. In particular, self-lubricating coatings have proven useful in aircraft and bearing industrial equipment, where severe operating conditions can occur. For example, aircraft fuel and oil pump housings require repair because their gear drive bushings wear away during use. This wear (called "galling" or "scoring" or "gear wiping") limits the longevity of the pump housing and requires their replacement or their rebuilding.
One method of rebuilding such pump housing is disclosed in U.S. Pat. No. 4,996,085 which issued to Sievers on Feb. 26, 1991. That patent teaches coating the pump housing surfaces to be treated with a composition comprising a hardenable epoxy resin, a reinforcing filler, and an agent having a lower coefficient of friction than the epoxy resin. It is noted col. 2, lines 44-45, suggest that graphite may function as the reinforcing filler. Col. 3, lines 43-54, of the reference also teaches the frictional reducing agent may be either graphite, in fibrous or granulated form; fluorinated carbon (i.e., --(CF.sub.x)-- wherein x&lt;2); or molybdenum disulfide. It is noted that this reference does not provide any further specifics as to the fluorinated carbon materials useful for that invention. It is also noted that the preferred class of epoxy resins in this reference are diglycidyl ether of a dihydric phenol (e.g., the diglycidyl ether of bisphenol A).
A second method of treating such worn pump housing surfaces is disclosed in U.S. Pat. No. 5,316,790 which issued to Chan et al. on May 31, 1994. This patent describes a lubricative coating and filler material for restoring metal surfaces that have scratched, scored, grooved, or otherwise damaged to a functional condition. This coating and filler material is a mixture of an epoxy resin, tungsten disulfide, and isopropyl alcohol in a ratio of 9:1:1.6.
While these coating materials may be satisfactory for certain applications, there is still need for a better self-lubricating coating compositions useful for a wide variety of applications including pump housing materials or pump housing repair compositions.